Background:

Gout is a disease caused by deposition of monosodium urate crystals in articular and periarticular tissues. Hyperuricemia has been reported to be closely linked to the development and recurrence of gouty arthritis. Although, theoretically, gout cannot develop without hyperuricemia, there have been reports of development of gout without hyperuricemia. And in the clinical setting, some patients receiving a urate-lowering agent for chronic gout have experienced recurrent attacks of gout without hyperuricemia.

Purpose:

To identify the factors associated with an acute attack of chronic gout without hyperuricemia.

Method:

We reviewed the medical records of 860 patients with chronic gout and who regularly received allopurinol at one tertiary hospital from 2003 to 2009. Among these 860 patients, 135 maintained a serum urate level less than 6.0mg/dl. To minimize the effect of serum urate level change, we excluded all patients whose serum urate level exceeded 6.0mg/dl at least once. We divided the study patients into an Attack group (n=51) and a No-attack group (n=84). The patients who experienced an acute attack, even though with normouricemia (<=6.0mg/dl) at least once during follow-up period, were classified as the Attack group. The others were classified as the No-attack group. We prescribed colchicine to prevent gout attacks during the first six months of the study, and attacks which occurred during this period were not included.

Results:

Fifty-one (37.8%) patients experienced at least one recurrence of an acute attack without hyperuricemia during the follow-up period (Attack group). The remaining 84 (62.2%) patients never experienced an acute gout attack (No-attack group). During the follow-up period, the sampling frequency was similar in the two groups. The baseline characteristics of the patients in each group, including age, alcohol drinking, hypertension, chronic kidney disease, heart disease, type II diabetes mellitus, diuretics, and aspirin therapy showed no significant difference in the two groups. The presence of tophi and the number of involved joints were strongly associated with acute attacks of chronic gout without hyperuricemia, respectively (OR 5.9, P=0.001 and OR 1.7, P=0.001). On multivariate analysis, the presence of tophi and the number of involved joints were also independently associated with acute attacks of chronic gout, respectively (OR 4.2, P=0.010 and OR 1.5, P=0.028).

Conclusion:

Our study revealed that the presence of tophi and multiple joint involvement were associated with acute attacks of chronic gout without hyperuicemia. We, therefore, recommend that patients with these risks should maintain a lower target level of serum urate.